1. Field of the Invention
The present invention relates to a filter using an exchangeable filter element. The filter can be used as a spin-on oil filter for, for example, filtrating impurities or the like mixed in lubrication oil for an internal combustion engine.
2. Description of Related Art
An exchangeable element type filter heretofore known is disclosed in Japanese Utility Model Application Laid-Open Publication No. 6-85007. In this filter construction, a filter casing is divided into two sections, and a projecting portion (an engaging projection) on one side is inserted into a groove portion (an engaging groove) on the other side so that rotation thereof causes connection of the casing to provide an assembly.
The aforementioned filter construction comprises a longitudinal groove having an axial direction aligned with the inserting direction and a subsequent lateral rotational direction at a right angle to the axial direction. An O-ring as a seal member is disposed on the removable portion, and an excessive force is applied to the O-ring when the casing parts are taken apart or connected. Accordingly, there is a disadvantage because since the O-ring is hard to be inserted and tends to be twisted, its sealing property is impaired, and the operating characteristics are not good.
Further, there is another disadvantage because in this filter construction, the engaging projection and grove shapes are easily moved in a rotational direction and in an axial direction after being mounted on the vehicle, and thus the casing becomes loosened and tends to be disengaged.